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  #1  
Old 04-18-2015, 08:02 PM
kosopet kosopet is offline
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Default Yamaha cs40m project

Hello, i plan to adapt umr2 to yamaha cs40m synth.
So, here scope photo with select signal from cs40m keyboard assigner.
The select signal looks like 10 volt wide from +5 to -5 volt, low active.
Also i include fragment of schematics related to keyboard assigner circuitry.
Give me please some advices about possible ways to adapt umr2 to cs40m, because it is cant suit directly as i understand now.
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  #2  
Old 04-18-2015, 08:05 PM
kosopet kosopet is offline
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Scope scales on the photo is 2v and 0.5ms.
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Old 05-02-2015, 04:42 PM
kosopet kosopet is offline
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Default dataline

Here a scope photo of signal from dataline itself, when no key pressed. So it is not plain voltage but there is signal from assigner ic dataline input. Let me know just some common approaches how to make adaptation for umr2 in this particular case.
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Old 05-04-2015, 04:59 PM
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Hi Kosopet, welcome to the forum.

Voltage level shifting is a difficult problem when it comes to interfacing with the UMR2.

The UMR2 operates on 5V (6VDC max). Any input signal on the UMR2 data or select pins must not be less than UMR2 ground, and must not be greater than the UMR2 power input voltage.

Do you intend to use the synthesizer as a sound module? Or do you want to use it as a MIDI controller? This will determine the specifics of the approach.
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Old 05-04-2015, 09:16 PM
kosopet kosopet is offline
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I plan to use synth as sound module indeed.
As for select lines i just tested zener diod on 5.1v with 1k resistor like that on picture in attachment. Out from this circuit is signal like that on my previous photo of scope from select line, but it is limited from +5v to -0,5v. Is it ok for select input of umr2, or this must be just +5v to 0v exactly ?
As about dataline input of key assigner ic which produce mentioned signal, just have no idea on this moment what should i do to make it suitable to umr2 specs.
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Last edited by kosopet; 05-04-2015 at 09:19 PM.
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  #6  
Old 05-16-2015, 06:11 PM
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Quote:
Originally Posted by kosopet View Post
I plan to use synth as sound module indeed.
As for select lines i just tested zener diod on 5.1v with 1k resistor like that on picture in attachment. Out from this circuit is signal like that on my previous photo of scope from select line, but it is limited from +5v to -0,5v. Is it ok for select input of umr2, or this must be just +5v to 0v exactly ?
As about dataline input of key assigner ic which produce mentioned signal, just have no idea on this moment what should i do to make it suitable to umr2 specs.
Your circuit for the select input to the UMR2 should probably work fine.

Since you will be using the UMR2 in "sound module" mode, that means that the data terminals will only be sending output from the UMR2 to the host keyboard. That makes things a little bit easier.

You will probably need a combination of transistors to get the right output signal from the UMR2 data lines to the key assigner.

Before I continue with that, are you certain that the lines B1..B8 are data signals (key assigner inputs) and that lines N1..N6 are select signals (key assigner outputs)? Can you tell me which signal from the schematic is shown in each of your scope photos?

I want to be as cautious as possible so that I don't give you bad advice.
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Old 05-17-2015, 05:49 PM
kosopet kosopet is offline
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My first scope photo show signal from B1..B8 terminals, it is select lines. My second scope photo show signal from N1..N6 terminals, it is data lines. Second scope photo show signal from data line when no key depressed, when i depress key signal from data line became same as on the select line.

Last edited by kosopet; 05-17-2015 at 05:52 PM.
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Old 05-17-2015, 09:43 PM
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Quote:
Originally Posted by kosopet View Post
My first scope photo show signal from B1..B8 terminals, it is select lines. My second scope photo show signal from N1..N6 terminals, it is data lines. Second scope photo show signal from data line when no key depressed, when i depress key signal from data line became same as on the select line.
Ah. Ok. Based on this information, it would seem that the select signal is therefore "active high". Notice the orientation of the diodes in the keyswitch matrix.

In other words, the select signals "pull up" the data lines when key switches are closed.

The starting point, then, is probably to use the -10 V rail as UMR2 ground (UMR2 V-). Then, use a zener diode and resistor to regulate the host's ground voltage down to -5 V for use as UMR2 V+. Does that make sense?

Then, you can use the zener diode circuit to limit the voltage on the UMR2 select inputs.

For connecting the UMR2 data pins to the data bus, perhaps a high-side driver like the MIC2981 can be used.

Does that all make sense?
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Old 05-18-2015, 08:16 PM
kosopet kosopet is offline
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Ok, i'll try bring your advices to life, than let you know which results i get. Thanks.
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Old 06-06-2015, 04:09 PM
kosopet kosopet is offline
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I dont understand something. Signal on host select line goes from -5 to +5 volt.
Why should i make -10 volt as umr2 ground and -5 volt as its +, if so ? May be i should make -5 volt as umr2 ground and host ground as umr2 + ?
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Old 06-06-2015, 04:38 PM
kosopet kosopet is offline
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One more question. According to umr2 setup procedure from its docs (point 7), i should press successively each key on the host keyboard.
So, when i press host key, on the host data line will present -5 to +5 volt signal form host select line, and this signal than goes
to umr2 data input. Should i limit this signal by zener diod or not, in the same manner as it is on the umr2 select inputs ?
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Old 06-06-2015, 04:46 PM
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Quote:
Originally Posted by kosopet View Post
I dont understand something. Signal on host select line goes from -5 to +5 volt.
Why should i make -10 volt as umr2 ground and -5 volt as its +, if so ? May be i should make -5 volt as umr2 ground and host ground as umr2 + ?
Perhaps. I'm not too familiar with these older types of digital logic that operate on such large voltages.

I simply noticed that Vdd is -10 V on the schematic and assumed the logic signals varied between +5 V and -10 V.

The main things are:

1) to set up the "level shifting" so that a logic "0" going into the UMR2 is at UMR2 V- (UMR2 ground) potential, and a logic "1" is at UMR2 V+ potential.

2) The difference between UMR2 V+ and UMR2 V- should be between 3 and 6 V.
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Old 06-07-2015, 10:20 AM
kosopet kosopet is offline
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Ok, can you please give me advice about my second question and umr2 setup procedure ?
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Old 06-07-2015, 03:20 PM
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Quote:
Originally Posted by kosopet View Post
One more question. According to umr2 setup procedure from its docs (point 7), i should press successively each key on the host keyboard.
So, when i press host key, on the host data line will present -5 to +5 volt signal form host select line, and this signal than goes
to umr2 data input. Should i limit this signal by zener diod or not, in the same manner as it is on the umr2 select inputs ?
Yes. Data signals to the UMR2 must be limited to between UMR2 V- and UMR2 V+, just like the select signals.

After the setup procedure is complete, assuming you will be using the UMR2 in "sound module" mode, you will need a different circuit so that UMR2 output from the data lines is the correct voltage for the host.

It is a tricky project!

Last edited by John; 06-07-2015 at 03:23 PM.
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Old 06-30-2015, 04:06 PM
kosopet kosopet is offline
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So, the story continues. I make power supply for umr as zener 4733a with 220om resistor. -Umr goes to zener and +umr goes to ground, so i get
supply voltage from -5 to 0. But scope shows this on the -umr node.
Is it ok that i have no straight line of -5 voltage but this variable from -4 to -4.5 ?
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  #16  
Old 06-30-2015, 04:08 PM
kosopet kosopet is offline
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Another problem. I make voltage limitation about 5 volt for dataline input, in order to make setup procedure for umr.
But on every dataline i hev just this scope picture.
Because, as I wrote earlier, dataline itself have some signal on it, and i am afraid that i need to find a way to cansel this
signal, to be able to make umr setup procedure.

Now when i try to make setup procedure, after sending lowest midi note from external midi keyboard, i can see that red led lights and green
red also randomly flashes.
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  #17  
Old 06-30-2015, 04:20 PM
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I'm not sure how much I can help with this. The variable "low level" logic voltage seen by the UMR2 could indeed cause problems. You can check out the PIC16F1939 datasheet to see the threshold voltages between a logic 0 and 1 on the UMR2.

To "clean up" the signals further perhaps you could use a logic buffer IC with Schottky inputs.

However, whatever signals make it to the UMR2, they should reflect only the keyboard matrix and the changes to the key states. If extra signals are happening on the data bus, then it can "confuse" the UMR2 and it may detect keystroke activity that isn't there. Thus the random flashing of the red LED during the setup procedure.

To summarize: it is a tricky problem to solve. Sorry that I can't make better suggestions.
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  #18  
Old 07-01-2015, 01:55 PM
kosopet kosopet is offline
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Ok, -5 volt rail now looking good, i just use 7905 ic to make appropriate voltage.
In order to avoid redundant signal on data lines i just disconnect dataline bus connector from synth pcb, so now dataline has -5 on it and when i push host key it has signal from select line. All it is quite good.

Now i am trying to make setup procedure.
When i try to goes to setup procedure where i sequentially push every key on host keyboard, i can see successful red led lights only when i push last 6 keys on the top of the keyboard. This keys connected to select line B8 on schematics. So i look with scope on signal from select line B8 and any other select line, there is a little difference in scope picture, i'll show it.
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  #19  
Old 07-01-2015, 01:57 PM
kosopet kosopet is offline
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here is scope picture of signal any select line from B1 to B7. Signal already limited by zener, it goes from -5 to 0 volt.
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  #20  
Old 07-01-2015, 02:00 PM
kosopet kosopet is offline
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And here signal from select line B8, there is just one difference in a little voltage drop in some places from 0 to about -0.5 volt.
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